1.WOT 2.Battery Box

Bajan · 27 April 2004, 11:39

Good morning all!
Could someone tell me what WOT is? I see this popping up in lots of conversations.

Also, I noticed the other day that after a day in the rough, my battery was soaked. I'm convinced that this isn't ideal. Can someone confirm or dismiss this for me. I saw plastic battery boxes at the Beaulieu Boat Jumble and wondered whether they were to prevent situations liuke that occuring.

Your info and advice, as always, is much appreciated.

Mike B · 27 April 2004, 11:42

Bajan,

WOT = Wide Open Throttle

As for battery boxes - I have one but battery is in console anyway so keeps dry. I would think it would be better to keep the battery as dry as possible by what ever means - is there any chance of making its current enclosure water tight ?

Mike

Louise · 27 April 2004, 11:44

Hi,

WOT means 'Wide Open Throttle' ie full acceleration.

I would try to prevent the battery getting soaked. Don't know how waterproof the battery boxes are but I think they are quite commonly used and should stop most of the water. Our battery is housed in the console. If your battery is being immersed in water, I would look at the location of your battery.

HTH.

Bajan · 27 April 2004, 13:07

Thanks for the info!
My battery is located in the front console as well, however there is an opening on the side of the console where the electrics run to other parts of the boat and I think that's where the water is entering. I am thinking of getting one of those rubber conical shaped boots(looks like a gearshift cover) and seeing if that will work. Any other suggestions welcome.

Matt · 27 April 2004, 15:26

Quote:

Originally Posted by Bajan

Good morning all!
Could someone tell me what WOT is?

Same as WFO

tim griffin · 27 April 2004, 17:22

Hi Bajan
not sure of your front console have you tried to build a battery box or can you not get access for this, any thing that keeps the water away from the battery is good the rubber boot sounds like a good idea! oh and when you feel the need for speed WOT
regards tim
www.griffmarineservices.co.uk

Tim M · 27 April 2004, 17:47

I'm after a rubber do dar for some cables too. I've been told it's called a "witches hat". Hope this helps

As for WOT, how long it is safe to run your engine at WOT without risking damage/premature failure/excess wear?

nugent · 27 April 2004, 18:28

any car spares dealer will sell you a rubber cv joint boot £5.00 does the job a treat... all sizes you can think of failing that make your own with a likkle hypalon and glue..

Bajan · 27 April 2004, 18:53

Thank you very much for the info guys!
I think I will get a battery box as well as the boot in order to cover all bases.

Quote:

Originally Posted by timofengland

As for WOT, how long it is safe to run your engine at WOT without risking damage/premature failure/excess wear?

From what I gather, (and if I'm wrong someone please tell me) as long as you're within the manufacturer's specified rev range, the worst result is a higher petrol bill. If you exceed the rev range then it becomes damaging to the engine. Can someone confirm or dismiss this?

Cheers

Bajan

codprawn · 27 April 2004, 19:08

The higher the revs the more wear there is on the engine - simple!

As to rev limits how long is a piece of string? If you look at the ratings for marine diesels you will see a huge difference between ratings for leisure and commercial use for the same engine. Something that is rated at 1000hp in a Sunseeker may only be rated at 400hp for constant uses in a commercial environment.

Maybe I am being cautious but i wouldn't want to run flat out on a leisure rated motor for more than an hour or so at a time without throttling back. Having said that it all depends on how the makers have rated the engine - the REAL rev limit could be a hell of a lot higher than they let on.

I have yet to blow up any kind of engine but I follow strict rules - carefull running in - plenty of warm up time before throttles start to be opened up - very regular servicing.

If you find you are running at WOT for long periods you need a bigger engine! Either that or it's too calm!

Bajan · 27 April 2004, 20:34

Codprawn!
Valid points!
Would the drastic difference in hp between commercial and leisure be due to different prop sizes therefore torque/output varies?

Hightower · 27 April 2004, 20:38

Battery box! Yes it is a good idea to keep it dry, but only essential if it's of the un-sealed lead acid type, a sealed gel type batt. will be quite happy to get wet provided that you grease the terminals well (corrosion). The other reason to house your Batt. is to protect it from things you might accidently drop on it, like an Alloy paddle or handle of your boat hook. This could not only physically damage your Batt. but also short out the terminals in worse case causing an explosion.

Good practice to place in a Box and put an Isolater on the top of the box as well, just as good measure.

Hope this helps.

Andy

Tim M · 27 April 2004, 20:38

Not knowing much about these things, I would have said it was purley stress to the engine; a 100hp downrated to an 80 for commercial use can be used at WOT for hours without it getting too worn. A 100hp for leasure use running at 100hp for hours would wear out more quickly....

gavin · 27 April 2004, 22:23

undefined
Quote
The higher the revs the more wear there is on the engine - simple

This is simply not true, the higher the engine revs, before redlining doesnt mean more engine wear, If you are not overrevving you are not harming the engine, when it is up to temperature.The higher the engine revs the faster the oil pump delivers oil and lubrication as per required, and coolant, marine engines are rated for constant horsepower afterall.A hard acceleration on a cold engine would be far worse than driving at full rpm.At full revs everything is warmed , oil is flowing , engine is still being cooled and still being lubricated, I would definately feel an engine is more liable to wear when driven hard cold , and immediateely after a start.Do you ever see the smoke out of a Trent or Severn class Lifeboat which are driven hard immediately from a cold start, thats an example of ring and cylinder wear, you are correct to let things warm up and service regulary, but its okay to drive at full rpm, provided you are staying out of the red.

Bajan · 27 April 2004, 22:30

Gavin!
What is an aceptable warming up period?

Hightower!
Thanks for the info! I think I might have an isolator which might have been disabled. I'll check it out.

gavin · 27 April 2004, 22:45

In the absence of a temp guage, you will hear the difference and feel the difference in a two stroke motor , from cold driving compared to when the motor is warm.I would let the motor idle for maybe less 6/7 mins feel the telltale to know when the motor is warming, there is nothing worse than cold accelerations on a motor

Matt · 27 April 2004, 22:48

Bore wear increases with the square of piston speed (therefore rpm). So the difference between 5000 rpm and 6000rpm is 20% (1.2) , bore wear rate increases by 44% (1.4).

Quote:

Originally Posted by gavin

undefined
Quote
The higher the revs the more wear there is on the engine - simple

This is simply not true, the higher the engine revs, before redlining doesnt mean more engine wear, If you are not overrevving you are not harming the engine, when it is up to temperature.The higher the engine revs the faster the oil pump delivers oil and lubrication as per required, and coolant, marine engines are rated for constant horsepower afterall.A hard acceleration on a cold engine would be far worse than driving at full rpm.At full revs everything is warmed , oil is flowing , engine is still being cooled and still being lubricated, I would definately feel an engine is more liable to wear when driven hard cold , and immediateely after a start.Do you ever see the smoke out of a Trent or Severn class Lifeboat which are driven hard immediately from a cold start, thats an example of ring and cylinder wear, you are correct to let things warm up and service regulary, but its okay to drive at full rpm, provided you are staying out of the red.

Matt · 27 April 2004, 22:52

I'm not 100% sure about this, but I would expect lifeboat engines to be preheated, and probably pre-oiled too. The bigger the engine, the bigger the problem of warming the engine up is as it can take days in big ships. That's why the navy favour gas turbines on many of their ships as they can safely produce full power within a few minutes of spooling up.

codprawn · 28 April 2004, 02:22

Quote:

Originally Posted by MadMat

Bore wear increases with the square of piston speed (therefore rpm). So the difference between 5000 rpm and 6000rpm is 20% (1.2) , bore wear rate increases by 44% (1.4).

Thanks for that Mat - I would have thought it was common sense...........

Suzuki416 · 28 April 2004, 11:02

Sorry MADMAT I'm still not entirely convinced of this.
Where did you find out this conclusion?
Conrod off set, size of piston, amount of cylinders, & 2/4 stroke are other factors that may cause more of an effect.

I do agree that sitting on or near the red line for hours on end is not that good for your engine BUT you are MORE likely to damage your engine by starting it & driving off staight away!

As CODPRAWN said 'If you find you are running at WOT for long periods you need a bigger engine! Either that or it's too calm!'
Agree with this also - where's that 90!

Pete